Introduce Display Compositor mojo interface. Use InProcessContextProvider.

services/ui/ws/frame_generator.h

Index: services/ui/ws/frame_generator.h
diff --git a/services/ui/ws/frame_generator.h b/services/ui/ws/frame_generator.h
index ed38ee24dad99e4e8491a23c48728f1c50f0f0f3..77a17e58d4ecf8628a3388f26de27ca0df5df041 100644
--- a/services/ui/ws/frame_generator.h
+++ b/services/ui/ws/frame_generator.h
@@ -10,12 +10,14 @@
 
 #include "base/macros.h"
 #include "base/timer/timer.h"
+#include "cc/ipc/display_compositor.mojom.h"
 #include "cc/surfaces/frame_sink_id.h"
 #include "cc/surfaces/local_frame_id.h"
 #include "cc/surfaces/surface_sequence.h"
 #include "cc/surfaces/surface_sequence_generator.h"
 #include "services/ui/public/interfaces/window_tree_constants.mojom.h"
 #include "services/ui/ws/ids.h"
+#include "services/ui/ws/server_window_delegate.h"
 #include "services/ui/ws/server_window_tracker.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/native_widget_types.h"
@@ -51,8 +53,6 @@ class FrameGenerator : public ServerWindowTracker,
   FrameGenerator(FrameGeneratorDelegate* delegate, ServerWindow* root_window);
   ~FrameGenerator() override;
 
-  void OnGpuChannelEstablished(scoped_refptr<gpu::GpuChannelHost> gpu_channel);
-
   // Schedules a redraw for the provided region.
   void OnAcceleratedWidgetAvailable(gfx::AcceleratedWidget widget);
 
@@ -96,7 +96,7 @@ class FrameGenerator : public ServerWindowTracker,
   // management.
   void ReleaseAllSurfaceReferences();
 
-  ui::DisplayCompositor* GetDisplayCompositor();
+  cc::mojom::DisplayCompositor* GetDisplayCompositor();
 
   // ServerWindowObserver implementation.
   void OnWindowDestroying(ServerWindow* window) override;
@@ -105,10 +105,8 @@ class FrameGenerator : public ServerWindowTracker,
   cc::FrameSinkId frame_sink_id_;
   ServerWindow* const root_window_;
   cc::SurfaceSequenceGenerator surface_sequence_generator_;
-  scoped_refptr<gpu::GpuChannelHost> gpu_channel_;
 
   cc::mojom::MojoCompositorFrameSinkPtr compositor_frame_sink_;
-  gfx::AcceleratedWidget widget_ = gfx::kNullAcceleratedWidget;
 
   struct SurfaceDependency {
     cc::LocalFrameId local_frame_id;